The present invention is directed to hot melt or phase change inks. More specifically, the present invention is directed to phase change inks particularly suitable for use in phase change ink jet printers. One embodiment of the present invention is directed to a phase change ink composition comprising (a) a colorant and (b) the reaction product of (i) an isocyanate and (ii) an antioxidant or UV stabilizer molecule having thereon (A) at least one isocyanate-reactive hydroxyl group and/or (B) at least one isocyanate-reactive primary or secondary amino group.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of each of which are totally incorporated herein by reference.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or a mixture of dyes. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. No. 4,889,560, U.S. Pat. No. 4,889,761, and U.S. Pat. No. 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking, industrial marking, and labelling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Compositions suitable for use as phase change ink carrier compositions are known. Some representative examples of references disclosing such materials include U.S. Pat. No. 3,653,932, U.S. Pat. No. 4,390,369, U.S. Pat. No. 4,484,948, U.S. Pat. No. 4,684,956, U.S. Pat. No. 4,851,045, U.S. Pat. No. 4,889,560, U.S. Pat. No. 5,006,170, U.S. Pat. No. 5,151,120, U.S. Pat. No. 5,372,852, U.S. Pat. No. 5,496,879, European Patent Publication 0187352, European Patent Publication 0206286, German Patent Publication DE 4205636AL, German Patent Publication DE 4205713AL, and PCT Patent Application WO 94/04619, the disclosures of each of which are totally incorporated herein by reference. Suitable carrier materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters, for example), and many synthetic resins, oligomers, polymers, and copolymers.
U.S. Pat. No. 5,750,604 (Banning et al.), the disclosure of which is totally incorporated herein by reference, discloses resins and waxes made by reacting selected nucleophiles, including alcohols and/or amines, with an isocyanate. The order of addition of the isocyanate and the different nucleophiles can tailor the distribution of di-urethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The isocyanate-derived resin and wax materials are useful as ingredients as phase change ink carrier compositions used to make phase change ink jet inks.
U.S. Pat. No. 5,780,528 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses isocyanate-derived colored resins made by reacting an alcohol and/or amine, an isocyanate, and a nucleophilic molecule containing a chromogen. The isocyanate-derived colored resins are useful as colorant materials in phase change ink compositions.
U.S. Pat. No. 5,782,966 (Bui et al.), the disclosure of which is totally incorporated herein by reference, discloses resins and waxes made by reacting selected nucleophiles, including alcohols and/or amines, with an isocyanate. The order of addition of the isocyanate and the different nucleophiles can tailor the distribution of di-urethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The isocyanate-derived resin and wax materials are useful as ingredients as phase change ink carrier compositions used to make phase change ink jet inks.
U.S. Pat. No. 5,783,658 (Banning et al.), the disclosure of which is totally incorporated herein by reference, discloses resins and waxes made by reacting selected nucleophiles, including alcohols and/or amines, with an isocyanate. The order of addition of the isocyanate and the different nucleophiles can tailor the distribution of di-urethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The isocyanate-derived resin and wax materials are useful as ingredients as phase change ink carrier compositions used to make phase change ink jet inks.
U.S. Pat. No. 5,827,918 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses resins and waxes made by reacting selected nucleophiles, including alcohols and/or amines, with an isocyanate. The order of addition of the isocyanate and the different nucleophiles can tailor the distribution of diurethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The isocyanate-derived resin and wax materials are useful as ingredients as phase change ink carrier compositions used to make phase change ink jet inks.
U.S. Pat. No. 5,830,942 (King et al.), the disclosure of which is totally incorporated herein by reference, discloses resins and waxes made by reacting selected nucleophiles, including alcohols and/or amines, with an isocyanate. The order of addition of the isocyanate and the different nucleophiles can tailor the distribution of diurethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The isocyanate-derived resin and wax materials are useful as ingredients as phase change ink carrier compositions used to make phase change ink jet inks.
U.S. Pat. No. 5,919,839 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses colored waxes made by reacting selected nucleophiles, including alcohol containing colorants, with an isocyanate. A phase change ink is made by blending the colored wax with a clear ink carrier composition. The clear ink carrier composition can be a fatty amide-based material and/or a combination of isocyanate-derived resins in which the order of addition of the isocyanate and the different nucleophiles can tailor the distribution of di-urethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The colored wax materials are useful as ingredients with phase change ink carrier compositions to make phase change ink jet inks.
PCT Application WO 94/14902, the disclosure of which is totally incorporated herein by reference, discloses a material suitable for use in a hot melt ink, having a melting point of at least 65° C. and obtainable by reacting an aliphatic or aromatic diisocyanate with an at least stoichiometric amount of: (i) a monohydric alcohol component; or (ii) a monohydric alcohol component followed by another different monohydric alcohol component; or (iii) a monohydric alcohol component, followed by a dihydric alcohol component followed by a monohydric alcohol component; the monohydric alcohol component(s) comprising a monohydric aliphatic alcohol or an etherified or esterified dihydric aliphatic alcohol or dihydric polyalkylene glycol; as the dihydric alcohol component comprising a dihydric aliphatic alcohol or a dihydric polyalkylene glycol and being used in an amount of not more than 50 percent of the stoichiometric amount of hydroxyl groups required to react with the isocyanate groups on the diisocyanate.
While known compositions and processes are suitable for their intended purposes, a need remains for improved phase change inks. In addition, a need remains for phase change inks with improved lightfastness. Further, a need remains for phase change inks with improved lightfastness wherein the improved lightfastness is not obtained at the expense of other desirable ink characteristics. Additionally, a need remains for phase change inks with improved lightfastness and with a high degree of transparency. There is also a need for phase change inks that have the advantages provided by antioxidant or UV stabilizer additives but wherein the antioxidant or UV stabilizer does not diffuse out from the colorant or from the rest of the ink composition. In addition, there is a need for phase change inks that have the advantages provided by antioxidant or UV stabilizer additives but wherein the ink does not exhibit undesirable properties such as plasticization or the like as a result of the present of an antioxidant or UV stabilizer. Further, there is a need for phase change inks that have the advantages provided by antioxidant or UV stabilizer additives but wherein the antioxidant or UV stabilizer does not bloom at the surface of images generated with the ink. Additionally, there is a need for phase change inks that have the advantages provided by antioxidant or UV stabilizer additives wherein the antioxidant or UV stabilizer moiety can be maintained in close proximity to the colorant moiety.